Signal coupling device



July 7, 1959 M. R. KRASNO SIGNAL COUPLING DEVICE Original Filed Dec. 1,1953 FIG. 4

INVENTOR MAXWELL R. KRASNO BY 90? ATTORNEYS iln S ates Pam z,s94, 231;SIGNAL COUPLINGVDEVICE V Maxwell R. Krasno, Chicago, Ill., assignor, bymes ne as" "SerialNo. 577,433 g I 1 Claim. ((Cl. 336-83 This inventionrelates to signal coupling devices and more particularly to devices forcoupling an electrical signalbetween rotating and stationary apparatus.

This application is a division of now abandoned appli cation Serial No.395,630, filed December 1, 1953, in the name of Maxwell R. Krasno forSignal Coupling Device. i

9m many electrical signaling installations such as underwater soundlocating apparatus, the signal generating units are mounted upon astationary base, but the signal transmitting and receiving units arerotationally mounted. It is necessary to couple the electrical signalsfrom the stationary to the rotating units' with a minimum of noise anddistortions In the past, slip rings have been used, but the noiseintroduced by the rubbing of the stationary brushes upon the rotatingrings .was often of the same 2,894,231 V, I Patented July 7, 1959 h ismounted within an annular groove 14 and has two leads order ofmagnitudeas the reflected signals, and difficulty was encountered indistinguishing between the signal and the noise.

The word stationary in this application refers to the relationship ofthe elements with respect to their supporting structure which may be aship or the like.

It is an object of this invention to provide a new and improved devicefor coupling electrical signals between stationary and rotatingapparatus.

' It is another object of this invention to provide a new and improveddevice for coupling electrical signals between stationary and rotatingapparatus, which device introduces substantially no noise into thesignals.

It is a further object of this invention to provide a new and improveddevice for coupling electrical signals between rotating and stationaryapparatus, which device contains no rubbing electrical conductors.

A still further object of this invention is to provide a new andimproved device for coupling electrical signals between stationary androtating apparatus, which device utilizes magnetic fields as thecoupling medium.

Other objects and advantages of the invention will hereinafter becomemore fully apparent from the following description of the annexeddrawings, "which illustrate a preferred embodiment, and'wherein: 1 Fig.l is a plan view of the coupling device'of this invention;

" Fig. 2 is a sectional view on line 2--2 of the device shown in Fig. 1;1

Fig.3 is 'a sectional view of a modification of the device' shown inFig. l;

"Fig. 4 is a sectional view of another modification of the'device shownin Fig. l; and

Fig. 5 is a sectional view of a further modification of the device shownin Fig. 1.

Identical elements in the various figures of the drawings are identifiedby identical reference numerals.

Referring to the drawings in detail, and more particularly to Fig. l andFig. 2, the reference numeral 11 designates a stationary base or supportupon which is mounted a cylinder 12 of magnetic material such as soft 15extending outward from the cylinder 12 for connection to otherapparatus.

A shaft 16, adapted to be rotated by a source of power (not shown),extends through an opening 17 in the base 11 and through an axialopening 18 in the cylinder 12. A second cylinder 21 also of magneticmaterial is mounted upon the shaft 16 to be rotated thereby and isseparated from the cylinder 12 by an airgap 22. An annular coil 23 ismounted within a coaxial groove 24in the cylinder 21 and has leads 25extending through the cylinder 21 for connection to other apparatus. Thecoils 13 and 23 are fixed in position in their respective grooves 14 and24 by surrounding masses of insulating material such as a syn theticresin. The cylinders 12 and 21, the shaft 16, and the coils 13 and 23are all coaxial.

In operation, signals to be coupled between rotating apparatus andstationary apparatus are fed into one of the two coils 13 or 23. Thesignal current flowing through the coil establishes a magnetic fieldwhich varies in the same manner as the current flow through the coil.The coils 13 and 23 have a common magnetic path which includes portionsof the cylinders 12 and 21 and the air gap 22. The magnetic fluxestablished by the signal current in one of the coils induces in theother coil a signal voltage which has. the same wave form as theoriginalsignal, and since the two coils 13' and 23 are coaxial and annular inform, the rotation of the coil 23 with respect to the coil 13 has noefiiect upon the signal. Thus, a signal is coupled between stationaryand rotating apparatus with substantially no additional noise introducedtherein.

Fig. 3 shows a modification of the invention, which modification reducesthe effect of varying spacingbetween the cylinders. A stationarycylinder 31 of a material having a low magnetic reluctance such as softiron is mounted upon a stationary base 30 and has a groove 33 in whichis mounted an annular coil 32. A shaft 46 extends through an opening 34in the base 30 and through an axial opening 35 in the cylinder 31 and isadapted to be rotated by a source of rotating power (not shown). Asecond cylinder 36, also of a material having a low magnetic reluctancesuch as soft iron, is mounted upon the shaft 46, to be rotated thereby,and is separated from the cylinder 31 by an air gap 37. An annular coil38 is mounted in a groove 39 in the cylinder36 coaxial with the shaft46.

The adjacent surfaces of the two cylinders 31 and 36 are shaped so thatthe air gap 37, seen in cross section, follows a path in which the airgap 37 is purposely lengthened to diminish its contribution to the totalmagnetic path, and a large part of this air gap 37 is made parallel tothe axis of rotation and is not appreciably affected by relative axialmotion ofthetwo cylinders 31 and 36. The cylinder' 31 has a cylindricaldepression 40 surrounding the shaft 46, and is spaced from amatingcylindrical projection 41 of the cylinder 36 by the air gap 37. A

projection 42 surrounding the depression 40 in the cylinder 31 is alsocylindrical in form and is spaced from a mating depression 43 in thecylinder 36. The coil 32 is mounted in its groove 33 in theprojection'42 of the cylinder 31, and the coil 38, arranged to beoppositethe coil 32, is mounted in a'groove 39 in the base of thedepression 43. The cylinder 31 has a depression 44 around its peripheryand is spaced from a projection 45 of the cylinder 36.

The modification shown in Fig. 3 operates similarly to that of Figs. 1and 2. As in the device of Figs. 1 and 2, a signal current is introducedinto one of the coils 32 or 38 and establishes a magnetic field whichvaries as the current in the coil. This magnetic field induces a voltagein the unenergized coil, which voltage also varies as the originalsignal. The configuration of the opposing faces of the cylinders 31 and36, having depressions and projections such that they define a tortuouspath for the air gap 37, has .the effect of minimizing the. compensatingchanges in the air gap. :37 for a displacement of one of the cylinders31 or 36 from the other cylinder. "Thus, if the cylinder 36 were mountedsuch that there were end play and it'would vary in distance from thecylinder 31, the sides of the facing projections 42 and 41 anddepressions 43 and 40 of the 'two cylinders31 and 36 remain spaced aconstant distance from each other, and along these portions the air gapwould not vary in width.

Fig. 4 shows a modification having a different configuration of thecoils, which configuration improves coupling between the ,coils. A coil51 in the form of two spaced concentric rings is mounted in a groove 52in a cylinder 50. Acoil53-inthe form of a single annulus, which ispositioned 'in the space between the .two concentric rings of the coil51, is mounted in a groove 54in a cylinder 55. The coil 53 extends intothe groove 52 in the cylinder 50, and the two rings of the coil 51extend into the groove 5.4 of the cylinder '55, thus providing a ,moreintimatecoupling between .the two coils than is provided by either ofthe modifications shown in Figs. 1, 2, or 3. The cylinder 50 is mountedupona base 59 and the cylinder 55 is secured to .a shaft 56 which passesthrough an opening 57 in .the'base 59 and an axial opening 58 in thecylinder 50 and is .adapted to be rotated by a source of power (notshown).

The device of Fig. 4 operates the same as the device shown in Figs. 1and ,2. A signal current is introduced into oneof the coils 52 or 53 andthe magneticflux established by the current flowing through theenergized coil induces a voltage, having the same waveform as theoriginal current, in the other coil. The additional lengths of the coils52 and 53 and the positioning of the coil 53 between the two portions ofthe .coil 52 provides improved coupling for higher induced signalstrengths in the induced Winding.

Fig. shows a modification .which incorporates the changes of both Figs.3 and 4. A cylinder 62 of magnetic material is mounted on .a base.61 andhas a cylindrical depression 65 adjacent a shaft 76, which shaft passesthrough an axial opening 78 in the cylinder 62. Aprojection 71 in whichis an annular groove 64 containing a coil 63 in the format twodiametrically spaced rings surrounds the depression 65. A cylinder 67 ofa magnetic material is mounted for rotation upon the shaft 76 and isspaced from the cylinder '62 by an air gap 68. The cylinder 67 has aprojection 66 and a depression 69 in mating relation with the depression65 and the projection 71 respectively of the cylinder 62. A coil 74 inthe form of a single ring is mounted in a groove 75 in the base of thedepression 69 and is positioned between the two rings of the coil .63.The coils 63 and 74 are of sufficient length to extend into the grooves75 and 64 respectively.

The operation of the device shown in Fig. 5 is similar to the operationof the afore-described modifications. A signal current is caused to flowin one of the two coils 63 or .74 and the magnetic field established bythe signal current induces in the other coil a voltage which has thesame waveform .as the original signal current. The shape and arrangementof the coils 63 and 74 provide improved coupling over the device ofFigs. 1 and 2 and the mating projections 71 and 73 and the de- 4pressions 69 and 72 reduce the effect of end motion the cylinder 62 to aminimum.

In each of the above described modifications, it is contemplated thatthe rotationally mounted cylinder be connected mechanically as well aselectrically to the rotating signal apparatusagvith which it is to beused and that the stationary eylinder be mounted stationarily withrespect to the rotating signal apparatus. The magnetic materialof thecylinders may be laminated ;in a manner well known in the art to reduceeddy current losses. The described modifications are intended ,for thecoupling of signals of frequencies which are sufiiciently low that ironcylinders may be used without undue hysteresis loss. If, however, it isdesired to couple signals of radio frequencies, the cylinders may -beformed of non-magnetic materials, and ofnon-conductors, such assynthetic resins, wood, ceramics, or powdered iron material.

Obviously, many modifications and variations of .the present inventionare possible .in .the light .of the above teachings. 'It is therefore tobe understood that within the scope of the appended claim the inventionmay .be practiced otherwise than as specifically described.

Whatis claimed is:

A-magnetic coupling comprising a horizontal support, a rotatable shafthaving an upper end portion extending through an aperture in saidsupport, an upper cylindrical magnetic core member having an axialpassageway therein fixedly received by the upper end portion of theshaft for rotation therewith and positioning the core member with itslower .face providing a space with the support, a lower stationarycylindrical magnetic core member having an axial passageway therein andfreely mounted about theshaft, said lower core member reposing on saidsupport and having its upper .face disposed in slightly spaced relationwith the lower face of the upper core member to pemit independentrotation of the upp r core member, a first annular channel communicatingthrough the lower face of the upper core member and coaxial with theshaft, a second annular channel communicating through the .upper face.of the lower core member coaxial with the shaft and vertically alignedwith the first annular channel, a pair of spaced annular coils securedin one of said channels and extending into the other channel, acooperating annular coil secured in .the other of said channels andextending between said pair of spaced annular coils in spaced relationwith each of said coils to provide .an air gap therewith, each of ,saidspacedcoils and said cooperating coil being of substantially the lengthof the combined depths of both said channels to provide substantialmagnetic surface coupling areabetween the ,coils, electrical connectionsextending from said coils in the one channel and through the supportingcore member and an electrical connection extending from said cooperatingcoil and through its supporting core member.

References Cited in the file of this patent UNITED STATES PATENTS

